Means for defrosting refrigerating unit



April 5, 1932. c. 'r. HOFFMAN 1,852,163

MEANS FOR DEFROSTING REFRIGERATING UNITS Filed Oct. 19, 1929 4 Sheets-Sheet 1 w/vwss s April 5, 1932. HOFFMAN 1,852,163

MEANS FOR DEFROSTING REFRIGERATING UNITS Filed Oct. 19, 1929 4 Sheets-Sheet 2 T0 MOTOR T0 BELL R/NGER TRANSFORMER TO //0 V.

CURRENT SUPPLY.

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gum: H1012 Charles April 5, 1932.

c. 'r. HOFFMAN 1,852,163

MEANS FOR DEFROSTING REFRIGERATING UNITS Filed Oct. 19, 1929 4 Sheets-Sheet TD SWRCE 0F CURRE N71 Jvwentor CharlesTHqffmn Ap 5, 1932. c. T. HOFFMAN MEANS FOR DEFROSTING REFRIGERATING UNITS Filed Oct. 19, 1929 4 Sheets-Sheet EVA PORA 7'0 R EVAPORATOR WITH/N PREDET'ERM/ TEMPERATURE LIM/Ts.

Charles THgI-fman,

E m 6 m w m m A M W F S M E M Patented Apr. 5, 1932 UNITED STATES CHARLES T. HOFFMAN, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR OF ONE- PATENT OFFICE HALF TO EMORY L. GEOFF, OF WASHINGTON, DISTRICT OF COLUMBIA IEANS FOR DEFBOSTING BEFRIGERATING UNIT Application fled October 19, 1929. Serial No. 400,888.

This invention relates to refrigeration, and more particularly to a novel means for defrosting the evaporator or refrigerating unit.

The present defrosting means is intended 3to be used on automatic refrigerators, such, for example, as the type including a cabinet having a cooling chamber for enclosing or housing the evaporator or refrigerating unit, the said refrigeratin unit being suitably connected with means or circulating a refrigerant through the same, together with means for maintaining the evaporator or refrigerating unit within predetermined temperature limits. That is to say, the present invention contemplates the provision of defrosting means operating in conjunction with the instrumentalities referred to but in addition to the usual thermal or pressure control switch means for maintaining the evaporator or cooling unit within predetermined temperature limits which maintains the usual refrigerating cycle. Therefore, it will be apparent that the present construction and arrangement may be readily applied to or em- 2 bodied in refrigerators having the essential elements pointed out and is intended to control or modify the usual refrigerating cycle to the extent that it will suspend such cycle for a sufiicient period to effect defrosting and then automatically restore the cycle to its usual automatic controls.

A primary object of'the present invention is to rovide a simple and practical means for e ectin defrosting in which the owner of the box 15 only requlred to press a button or its equivalent when the eva orator or refrigeratlng unit becomes thick y coated with ice and then give the matter of defrosting no further consideration. When the defrosting has been completely accomplished the refrigerating cycle will he quickly restored, thereby avoiding undesirable delay in restoring the refrigerating cycle after defrosting, which frequently occurs where defrosting of the refrigerating unit and the restoration of the refrigerating cycle are both efiected manually.

According to the present methods, when it is desired to defrost the evaporator of a refrigerating unit, particularly of the household type, it is customary for the owner or user of the box to break the circuit to the refrigerating motor and leave the circuit open or broken until the unit is cleared of ice, thus requiring constant watchin of the box to determine when the ice has me ted away or should the owner of the box neglect to perform this operation, the temperature of the box might rise to such an extent that the contents would be spoiled or, at least, an unsafe temperature condition would exist in the box before the owner or user attempted to restore the refrigeratin cycle.

Under ordinary con itions the accumulation of ice or frost on the evaporator is visible or otherwise known to the user and when this condition of the box is observed according to the present invention, it is only necessary to operate a push button or equivalent manual element which will cause the circuit to the refrigerating motor to be opened, whereupon the owner may thereafter leave the box entirely alone and, when the tem erature rises to a predetermined point, and t e ice is melted away, the circuit to the refrigerating motor will be automatically restored by a thermally controlled device located in the box.

A further object of the invention is to provide means for mechanically indicating whether the refrigerator is in operation or whether it is defrosting.

With the above and other objects in view which will more readily appear as the nature of the invention is better understood, the same consists in the novel construction, combination and arrangement of parts hereinafter more fully described, illustrated and claimed. I

A preferred and practical embodiment of the present invention is shown in the accompanying drawings, in which:

Figure 1 is a detail view of the top portion of arefrigerator showing the push button and visual indicator on the upper panel.

Figure 2 is a vertical sectional view illustrating the relative location of the switch for controlling the motor circuit and the automatic or thermal switch carried by the refrigerating unit.

Figure 3 is a diagram illustrating the circuits involved.

Figure 4 is a detail plan view illustrating a mechanical type of indicator which may be utilized for showing the status of the refrigeratin g mechanism.

Figure 5 is a detail side elevation of the ap aratus shown in Fi re 4.

igures 6 and 7 are etail elevations of the indicating or signal window illustrating the two mom 1' according to whether the same is in full or dotted lines, as shown in Figure 5.

Figure 8 is a diagrammatic view illustrating a modification of the invention which in cludes a manually operated push rod for effecting the opening of the switch and the automatrc means for closing the same.

Figure 9 is a view of a refrigerator illustrating the a plication of the invention.

Similar re erence characters designate corresponding arts throughout the several figures of the rawings.

According to the embodiment of the invention illustrated in the drawings, it is proposed to e uip the evaporator or refrigerating unit esignated generally as A with a thermostat switch device A, the same being preferably fixed to a suitable part of the evaporator such as, for example. a baffle plate, coil guard or casing, and which, during the refrigerating cycle, is maintained in a normally open position, thereby permitting the continuation of the refrigerating cycle, and consequently permitting the building up of frost or ice on the evaporator until the user of the box observes that too much ice is on the unit.

When the above condition occurs, it is only necessary for the owner of the box to actuate a suitable manually manipulated element such, for example as a switch or circu t closer S, preferably located on an outside panel C of the box, designated generally as D, whereby the circuit to the motor M of the refrigcrating apparatus will be caused to be broken. The switch or circuit closer is preferably of the push button type so that when the button is pressed inwardly. suitable means will be actuated to break the circuit to the motor M and the motor circuit w ll be switched onto the line which includes the automatic circuit closer B.

When the circuit to the refrigerating motor is broken and the circuit of the refrigerating fluid in the evaporator ceases to circulate, the evaporator A will tend to warm up and the ice thereon will melt. When the ice has melted away and a predetermined temperature above ice temperature is reached in the box, the thermostatically controlled arm 25 will move over to the contact 27 and close the motor switch thereb to continue the refrigerating cycle automatically and without manual attention.

' button 1 may be ressed a lpasitions of the shutter or indicating When it is again desired to defrost, the gain andthe switch which controls t e motor will be automatically actuated to open the motor circuit, thereby permitting the defrosting of the evaporator to occur.

Referring more particularly to the means for carrying the invention into eflect, it will be observed that the automatic circuit closer A, which is fastened in any suitable manner to a part of the evaporator or box, includes a movable arm '25 controlled by a thermostat 26 which causes the same to move toward and from the contact 27. The arm 25 and the contact 27 are included in an electrical circuit to be presently described, and the arrangement of the thermostat element 26 is such 4 that when the evaporator is in use, the arm 25 will occupy the position shown in Figure 2, that is out of engagement with the contact 27. However, when the temperature of the box rises after defrosting has occurred the arm 26 will move into engagement with the contact 27, and thus automatically close a circuit which will actuate means to move the switch arm F. It will, of course, be understood that the automatic circuit closer A may be located and secured or supported at any convenient and suitable point on or near the evaporator. It may be at the back, or on the side, or, as indicated in the dra on the front of the evaporator. The location on the evaporator is immaterial so lon as it is in position responsive to roper co (1 conditions which will maintain the arm 25 away from contact 27 during normal operation of the box.

The arm 25 is electrically connected with the wire 25a and the contact 27 is electrically connected with the wire 270 which ma be led through a suitable conduit .or tube to the housing H preferably located in a wall of the refrigerator. With reference to the automatic circuit closer A it is pointed out that it is stationary or non-movmg, and it makes no difference if the ice builds onto or forms thereabout, so far as the operation and functioning thereof is concerned. As a matter of fact, it is desired to locate the same at a point where the cold is most intense whether it is directly on the metal of the evaporator or the ice itself, so that under all conditions. of normal operation the arm 25 will be out of engagement with contact 27.

As previously indicated, the switch arm for controlling the motor circuit is designated generally as F and is pivotally supported as indicated at 2 coaxially with an actuating arm B which is connected by a spring G with the arm F in such a way that when the arm F is struck or engaged at either side of its pivot 2, it will be thrown alternately against the contacts 31 and 31a which are respectively the terminals for the refrig- Ill erating motor circuit and the indicating circuit 32 which-includes the lam L.

The switch arm F is thrown rom the full .line position shown in'Figure 3 to the dotted 5 line position by the dogs 0 and O alternately engaging therewith at op ositesides of its axis, when the heads of said dogs are alternately engaged by the head of the plunger P carried by the armature elements N actuated by the magnets M.

Referring to Figure 3 of the drawings which illustrates diagrammatically the arrangement of parts and the circuits involved, the latter may be traced as follows;

* Assuming that the contact 30 of the switch arm F is in engagement with the terminals 31 of the motor circuit :0, thus closing the circuit to the refrigerating motor for normal operation, and the evaporator of refrigerating unit is coated with frost or ice, it is desirable to remove the same or defrost. To effect this operation it is only necessary to close the switch S by pressing the button 1 thereof whereupon current will flow from the source of electrical energy connected to the terminals y over the wire a to the magnets M and thence through wires 25b and 250 through the circuit closer or switch S to the wire 25d. This wire 25d is connected to the arcuate member 28 which is 'in turn 2611. Thus, when the circuit is closed'through the manipulation of the push button 1 of the switch S as just described, the magnets M will be energized and the plunger P will pull the dog 0 forwardly to move the arm F from the full line position shown in Figure 3 to the dotted line position, that is, away from the motor terminals 31 and toward and against the terminals 31a of the indicator circuit which includes the lamp L or equivalent indicator.

The switch arm F, after the manual ac tuation the push button 1 remains in the dotted line position shown in Figure 3 until the ice melts away from the evaporator or refrigerating unit and the arm 25 of the thermally controlled switch A moves over into engagement with the contact 27 When the above condition occurs, namely when the circuit is closed between 25 and 27,

the current flows over the following path,

omitting the circuit closer or push button S entirely; 7

From the source the current flows over wire 25a through magnets M to 'wire 25?) and thence to Wire 2513 which is directly connected with the arm 25, and which is now in engagement withcontact 27. The contact 27 is connected by wire 27 a with the arcuate member 28a, and since spring contact 29 of the arm F is now in engagement with the arcuate member 28a, the current will pass back to the source through wire 26a. In following this path, the magnets M will draw the armatures N toward their cores and actuate the plunger P to engage the dog 0' and thus throw the switch arm 'F back to its original position, that is away from the terminals 31a and against the terminals 30 to immediately restore the refrigerating motor in circuit and continue the normal operation of the box.

From the foregoing, it will be apparent that the matter of effecting defrosting is entirely under the control of the user of the box. That is to say defrosting can be accomplished at any time desired which has the advantage of enabling the user of the box not to find the box in a defrosting condition when it might be desired to use the same Furthermore, the arrangement provides for the use of the cold control feature which enables the user of the box to change the degree of cold at will, without any interference whatever from the defrosting apparatus with the cold control mechanism, thereby permitting tghe free and unhampered functions of the While the present application illustrates an electrical type of indicator for showing that the evaporator or refrigerating unit is being defrosted, nevertheless it may be pointed out that it is within the scope of the invention to use a mechanical indicator so that the user of the box may, at all times, be acquainted with its condition.

Accordingly I have shown in Figures 4 to 7 of thedrawings a simple and practical form of mechanical indicator which may be operated directly from the actuator for the switch arm F. This mechanism includes a rod or link 5 connected at its opposite end with the arm 6 of a bell crank lever which may be suitably supported by a bracket 7 or the like in the box preferably near the front wall thereof. The arm 8 of the bell crank lever has suspended therefrom a shutter or signal plate 9 adapted to be shifted behind a window 10 which may be placed on the panel C of the box. This plate may bear the legends Refrigerating and Defrosting in superposed relation. or if desired different colors may be used to indicate these conditions of the box. When the member 9 is in the elevated position shown in Figure 5 the Word Refrigtion shown in Figure 5 effects the movement of the rod or link 5 to cause the bell crank to shift the shutter or signal from one position to the other.

In connection with the source of current supplied to the terminals 3 it is pointed out that this depends largely upon the t of electrical actuatin means emplo e If magnets of the type indicated in the rawings 1 tuted for the magnets, the usual 110 volt alternating current may be used.

Fi re 8 of the drawings illustrates a modification of the invention wherein the manually operated means for opening the motor switch is mechanical instead of electrical.

That is to say, it is within the scope of the invention to utilize in place of the manually 0 rated electrical circuit closer, a push rod w ich may be moved to open the switch while the thermostatically operated circuit closer is utilized to close the motor switch.

Referring more in detail to Figure 8 the panel of the refrigerator is designated as C, the same having an opening therem for receiving the end of a shiftable rod Rwhich may be exposed at the face of the cabinet n the form of a button. The inner end of th s rod is connected as at 40 with the arm F. When the switch arm F is in contact with the motor terminals 31 the end of the rod has suflicient projection beyond the face of the panel C to enable the operator to push the same inwardly to move the spring tensioned arm F beyond center and snap the same int enga ment with the contacts 310 of the indicating circuit. This will break the circuit to the motor and permit defrosting to occur. When the ice melts away and the unit A warms up to the predetermined temperature, the arm 41 of the thermostat circuit closer A2 located on or adjacent the unit A will engage with contact 42 and close the circuit through the electrical actuators or magnets M via wires 43 and 44 thus causing the plunger P to engage with the head of the dog 0' to pull the same forwardly and cause the dog to throw the arm F away from the terminals 31a and against the terminals 31. The effect of this will be to move the arm B2 back to the dotted line position shown in Figure 8 and push the rod R sufficiently beyond the surface of the panel C to be ready for the next actuation.

From the foregoing it will be apparent that a novel and distinctive feature of the present invention resides in providing a simple push element located conveniently at a point on the exterior of the refrigerator which may be pressed by the user of the box whenever it is desired to defrost the evaporator, and thereafter no further manual attention is required until it is again desired to defrost. This arrangement provides a simple, practical and thoroughly reliable means for removing all of the hazards incident to defrosting from the use of the refrigerator.

Without further description, it is thought that the many features and advantages of the invention will be readily understood, and that changes may be resorted to within the scope of the appended claims, without departing from the spirit or scope of the invention.

I claim:

1. In a refrigerator, an electrical switch for controlling the motor circuit, an electrical actuator therefor, means for manually closing the circuit to said electrical actuator, and means controlled by temperature within the cooling compartment for closing a circuit'to the electrical actuator to restore the electrical switch to its normal position.

2. In a refrigerator, an electrical switch for the motor, an electrical actuator therefor, a push button type switch included in circuit with the electrical actuator for manually o crating the same to open the circuit to t e motor, and a thermal switch device located in the cooling compartment of the refrigerator and included in an electrical circuit with the electrical actuator, said thermal switch device being adapted to momentarily close the circuit to the electrical actuator.

3 In an electrical refrigerator, the combination with the motor of the refrigerating apparatus and the evaporator, of a motor control switch, an electrical actuator for the motor control switch, a manually operated circuit closer in circuit with said electrical actuator, and a thermally controlled switch responsive to box temperature also included in circuit with the electrical actuator, means whereby upon the closing of the manually operated circuit closer the motor control switch will be opened, and means whereby upon the operation of the thermally controlled circuit closer, the motor control switch will be closed.

4. In an electrical refrigerator, the combination with the evaporator and the motor concealed within the refrigerator housing, of an exterior panel of the refrigerator, a switch for the motor, a manually actuated device located on said panel, means connected with said manually actuated device for opening said switch to said motor, indicating means on the panel operatively connected with said switch for the motor to indicate whether the evaporator is in its refrigerating cycle or defrosting.

5. In an electrical refrigerator, means for effecting the defrosting of the evaporator including a motor control switch, manually controlled means for throwing said switch, thermally controlled means also for throwing said switch, and indicating means associated with said motor control switch for indicating whether the motor and evaporator are capable of performing the refrigerating cycle or Whether the evaporator is defrosting.

6. In an electrical refrigerator, the combination with the evaporator, means for circulating a refrigerant in the evaporator, means for maintainin the evaporator within predetermined varia le temperature limits, and a current supply line for furnishing current to said two last named means, of a member for making and breaking the circuit in said current supply line, manually operated means for actuating said member tobreak the circuit in said current supply line, and automatic means for actuating said member to restore the circuit in said current supply line.

7. In an electrical refrigerator, the combination with the evaporator, means for circulating a refrigerant in the evaporator, means for maintaining the evaporator Within predetermined variable temperature limits, and a current supply line for furnishing current to said two last named means, of a member for making and breaking the circuit in said current supply line, manually operated means for actuating said member to break the circuit in said current supply line, and automatic means responsive to box temperature for actuating said member to close the circuit in said current supply line.

8. In an electrical refrigerator, the combination with the evaporator, means for circulating a refrigerant in the evaporator, means for maintaining the evaporator within predetermined variable temperature limits, and a current supply line for furnishing current to said two last named means, of a member for makingand breaking the circuit in said current supply line, manually operated means for actuating said member to break the circuit in said current supply line, and thermall controlled means for actuating said mem er to close the circuit in said current supply line.

9. In an electrical refrigerator, the combination with theevaporator, means for circulating a refrigerant in the evaporator, means for maintaining the evaporator within predetermined variable temperature limits, and a current supply line for furnishing current to said two last named means, of a member for making and breaking the circuit in said current supply line, manually operated means accessible from an exposed face of the refrigerator for actuating said member to open the circuit in said supply line,- and a thermally responsive switch device located within the refrigerator and operatively connected withsaid member to cause its actuation to close the circuit in said current supply line. a

10. In an electrical refrigerator having an evaporator, means for circulating a refrigerant therein, means for maintaining the evaporator within predetermined temperature limits, and a current supply'line for furnishing current to said two last named means, means for effecting the defrosting of the evaporator including a switch for making and breaking the circuit in' said current supply line, manually controlled means for throwing said switch to 0 en position, thermally controlled means or throwing said switch to closed position, and indicating means connected to the switch for indicating whether the evaporator is performing the re frigerating cycle or capable ofdefrosting.

11. In an electrical refrigerator having an evaporator, means for circulating a refrigerant therein, means for maintaining the evaporator withinpredetermined temperature limits, and a current supply line for furnishing current to said two last named means, means for effecting the defrosting of the evaporator including a switch for making and breaking the circuit in said current supply line, manually controlled means for throwing said switch to open position, thermally controlled means for throwing said switch to closed position, and mechanical indicating means connected to the switch for indicating the position thereof and whether the eva orator is performing the refrigerating cyc e or capable of defrosting.

12. In an electrical refrigerator having an evaporator and means for circulating a refrigerant therein, means for maintainlng the evaporator within predetermined temperature limits, and a current supply line for furnishing current to said two last named means,

of means for eifecting'the defrosting of the evaporator including a switch, manually controlled means for throwing said switch to 'open position, thermally controlled means for throwing said switch to closed position, and indicating means associated with said switch for indicating whether the evaporator is refrigerating or capable of defrosting, said indicating means including a shiftable indicator member and actuating means between said shiftable indicator and the switch.

13. In an electrical refrigerator having an evaporator and means for circulating a refrigerant therein, means for maintaining the evaporator within predetermined variable temperature limits, and a eurrentsupply line for furnishing current to said two last named means, of a switch for making and breaking said current in said supply llne, means for automatically actuating sa1d switch to make the circuit in the current supply line, and means for manually actuating said switch to break the circuit in the current supply line, said last named means constituting an indicator for showing whether the evaporator is refrigerating or capable of defrostlng.

14. In an electrical refrigerator, the combination with the evaporator, means for circulating a refrigerant in .the evaporator, means for maintaining the evaporator within predetermined variable temperature limits, and a current supply line for furnishing current to said two last named means, of a member for opening the circuit in said current supply line for a period to effect defrost- 6 nuance 

